Method for producing glass fibers

Abstract

A cooling system for establishing and maintaining the running mode of a bushing used in production of glass fibers which embodies a heated orifice plate with closely spaced orifices and a bulk flow of upwardly directed gas (e.g., air), which cooling system comprises a series of opposing nozzles which provide a multiple air lance effect in starting up, clearing and maintaining the flow of individual glass fibers through each orifice.

What we claim is: 
     
       1. The method of establishing the running mode of a glass fiber producing orifice plate having orifice plate heating means and closely spaced orifices comprising: (a) permitting molten glass to flood the underside of the orifice plate;   (b) establishing the temperature of the orifice plate to provide a glass viscosity at the orifices of more than about 1000 poises;   (c) forming a matrix of glass on the underside of the orifice plate;   (d) directing cooling gas to the underside of said orifice plate from a plurality of nozzles located along each of at least two sides of the orifice area, said nozzles being at an angle of from about 30° to about 60° to said orifice plate, being in generally opposed relationship, being closely adjacent said orifice area, and being directed generally to the center of the plate, said cooling gas flow having a total cross-section at the orifice plate at least as large as the area occupied by orifices;   (e) slowly withdrawing said matrix of glass from said orifice plate while increasing the temperature of said orifice plate and regulating the flow of said cooling gas to form fiber-forming cones under at least some of the orifices in said orifice plate; and   (f) periodically slowly decreasing and increasing the flow of cooling gas over the entire orifice area, said decreases in gas flow being sufficient to permit isolated flooded areas to flow to adjacent fiber forming cones and said increases in gas flow being sufficient to increase the viscosity of the glass to cause flooded areas to fiberize as fibers are drawn from adjacent fiber forming cones to progressively clear additional portions of the orifice area with each variation.   
     
     
       2. The method of claim 1 wherein said nozzles are located around the entire periphery of said area occupied by orifices in said orifice plate. 
     
     
       3. The method of establishing and maintaining the running mode of a glass fiber producing orifice plate having orifice plate heating means and closely spaced orifices comprising: (a) permitting molten glass to flood the underside of the orifice plate;   (b) establishing the temperature of the orifice plate to provide a glass viscosity at the orifices of more than about 1000 poises;   (c) forming a matrix of glass on the underside of the orifice plate;   (d) directing cooling gas to the underside of said orifice plate from a plurality of nozzles located along each of at least two sides of the orifice area, said nozzles being at an angle of from about 30° to about 60° to said orifice plate, being in generally opposed relationship, being closely adjacent said orifice area, and being directed generally to the center of the plate, said cooling gas flow having a total cross-section at the orifice plate at least as large as the area occupied by orifices;   (e) slowly withdrawing said matrix of glass from said orifice plate while increasing the temperature of said orifice plate and regulating the flow of said cooling gas to form fiber-forming cones under at least some of the orifices in said orifice plate;   (f) periodically slowly decreasing and increasing the flow of cooling gas over the entire orifice area, said decreases in gas flow being sufficient to permit isolated flooded areas to flow to adjacent fiber forming cones and said increases in gas flow being sufficient to increase the viscosity of the glass to cause flooded areas to fiberize as fibers are drawn from adjacent fiber forming cones to progressively clear additional portions of the orifice area with each variation; and   (g) adjusting said nozzles so that the cooling gas streams impact below but closely adjacent to said orifice plate to create a turbulent bulk flow of upwardly more gas at the cone and plate area, whereby cone separation is maintained.   
     
     
       4. The method of claim 1, wherein said nozzles are at an angle of about 45° to said orifice plate. 
     
     
       5. The method of claim 1, wherein said nozzle outlets are located on two sides of said orifice area at a distance of from about 2 to about 5 inches from the center of said orifice area. 
     
     
       6. The method of claim 1, wherein said nozzles have an inside diameter of from about 1/32 to about 1/2 in.